The present invention relates generally to woven fabrics and, more particularly, to woven fabrics that comprise at least one section of weave that is prone to raveling when cut, this section being bounded by a perimeter of weave that is less prone to raveling. The weave sections that are less prone to raveling provide areas where the woven fabric can be cut to provide a border area that is less susceptible to raveling than the bounded raveling-prone area.
Three-dimensional (3-D) woven fabrics are commonly used in many various industrial applications. For example, 3-D woven fabrics are used as filters, separators, and moisture coalescing surfaces. The present invention is more particularly directed toward providing an improved woven fabric for use in these and other applications in which 3-D woven fabrics could be advantageously employed.
An inherent problem with 3-D woven fabrics is that their weave patterns are such that they ravel rather easily. When 3-D fabrics are cut into pieces during the fabrication of a useful part for a given application, the cut edges have a high tendency to fray causing the threads of the woven fabric to ravel from the edge. This increased tendency to ravel is due, at least in part, to the structure of the weave pattern within the 3-D fabric. In a 3-D woven fabric, there is not enough yarn or filament mass in the weave pattern to allow for sufficient bonding and sealing of the fabric yarns to prevent fabric fraying.
Current methods employed to prevent fraying include the application of heat to the cut ends of a 3-D woven fabric to thermally bond the yarns in the fabric to one another. Alternatively, or in combination with thermal bonding, the cut edges of a 3-D woven fabric are commonly rigidly affixed within a frame. The frame is employed to grip the multitude of exposed yarns at the cut edge surface and thereby prevent their motion relative to one another in order to prevent the raveling of the fabric. However, a problem in the prior art is that 3-D fabric is difficult to place within a frame because 3-D fabrics tend to ravel when being manipulated in conjunction with placement in these frames. Thus, at the internal perimeter of the frame, the yarns of the 3-D weave may be raveled at the area proximate the frame members such that the utility of the 3-D fabric can be substantially compromised.
Flat weave fabrics tend to resist raveling much better than 3-D fabrics because the yarns of a flat weave fabric are more densely woven than the yarns of a 3-D woven fabric and therefore better able to bond and seal to prevent fabric fraying. Examples of basic flat weaves include plain, satin, and twill weaves. It is generally known that most flat weave fabrics have the ability to retain sufficiently sealed edges when cut. Additionally, flat weave fabrics do not tend to ravel within frames as do 3-D woven fabrics. Thus, it has been discovered, and is herein disclosed, that the shortcomings discussed hereinabove with respect to 3-D fabric can be substantially overcome by providing a woven fabric having 3-D weave sections bounded by flat weave sections.
It should be appreciated, however, that 3-D fabrics are not the only fabrics that contain weave patterns susceptible to raveling when cut. Indeed, even some weave patterns that would normally be considered flat weave exhibit a tendency to ravel when cut. Accordingly, while the focus of the best mode for carrying out the present invention is on employing 3-D weave and flat weave in combination, it should be understood that the teachings herein can readily be adapted and applied to provide, more generally, a woven fabric using in combination, a weave having a tendency to ravel when cut (herein termed a xe2x80x9craveling-prone weavexe2x80x9d) and a weave that tends to resist raveling when cut (herein termed a xe2x80x9craveling-resistant weavexe2x80x9d). Non-limiting examples of raveling-prone weaves include honeycomb weave, diamond weave, basket weave, and various rib weaves.
As is generally known, most woven fabrics are manufactured on large width looms, on the order of 12 feet or so across. For various applications, the fabrics may be cut, such as for instance, to length, as well as into shorter widths. For some weave patterns, the cut ends will ravel unless subsequently treated or bound. By weaving a raveling-resistant weave section around other sections having raveling-prone weaves, fabrics according to the present invention can be provided where raveling and post-weave operations are substantially reduced if not eliminated altogether.
Thus, there exists a need in the art for a woven fabric providing woven sections prone to raveling when cut in combination with woven sections that are raveling-resistant, such that the fabric can be employed in industrial applications requiring the raveling fabric, (e.g. 3-D woven fabric), and yet still prevent raveling and be able to remain whole when placed in a frame.
In light of the foregoing, it is an object of the present invention to provide a woven fabric using a raveling-resistant weave in combination with a raveling-prone weave.
It is also an object of the present invention to provide a woven fabric, as above, having at least one raveling-prone weave section that is completely bounded by a raveling-resistant weave such that the raveling-resistant weave defines the shape of the at least one raveling-prone weave section.
It is yet another object of the present invention to provide a woven fabric, as above, wherein the raveling-resistant weave can be cut with a hot knife, laser, ultrasonic, or other similar cutting device and still substantially resist raveling at the cut edges.
It is another object of the present invention to provide a woven fabric, as above, wherein the cut edges of the raveling-resistant weave can be placed within a frame and resist raveling proximate to the frame members.
It is an object of the present invention to provide a woven fabric, as above, in which the raveling-resistant weave is flat weave and the at least one raveling-prone weave section is a 3-D weave section.
It is still yet a further object of the present invention to provide a woven fabric, as above, wherein the yarns of the at least one 3-D weave section are woven in a honeycomb, diamond, or double cloth, pattern.
It is an object of the present invention to provide a woven fabric, as above, wherein the yarns of the flat weave sections are woven in a plain, twill, or satin pattern.
Yet another object of the present invention is to provide a filter element comprising a frame carrying a combination woven fabric as set forth herein.
Additionally, it is an object of the present invention to provide a method for the production of a woven fabric exhibiting one or more of the aspects of the present invention as outlined above.
At least one or more of these objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements herein described and claimed.
In general, a woven fabric made in accordance with the present invention includes at least one raveling-prone weave section bounded by raveling-resistant weave to define the shape of the raveling-prone weave section.
Other aspects of the present invention are accomplished by a method for creating a woven fabric having a plurality of raveling-prone weave sections, each surrounded by a perimeter of raveling-resistant weave, comprising programming a desired weave pattern into a dobby to weave the raveling-prone weave sections of the fabric in a prescribed pattern and change the weave to that of the raveling-resistant weave when the desired length of those raveling-prone weave sections is reached; drawing warp ends corresponding to the raveling-prone weave sections on harness frames separate from those harness frames associated with warp ends corresponding to the raveling-resistant weave such that the warp ends of the raveling-prone weave sections can be independently raised or lowered by their associated harness frames; weaving fabric according to the prescribed pattern in the dobby; and providing raveling-resistant weave in the warp direction by independently raising and lowering warp ends associated with the raveling-resistant weave.
Finally, the present invention provides a filter element comprising a frame member; and a woven fabric providing at least one raveling-prone weave section surrounded by raveling-resistant weave such that the raveling-resistant weave defines the shape of the at least one raveling-prone weave section